public override Expression Optimize()
{
bool somethingChanged;
Expression previous;
IList <Expression> oldList = ConcatHelper.Iterate(Expressions.Select(e => e.Optimize())).ToList();
IList <Expression> newList;
do
{
somethingChanged = false;
newList = new List <Expression>();
previous = null;
foreach (Expression expression in oldList)
{
if (expression == Empty.Instance)
{
somethingChanged = true;
continue;
}
if (previous == null)
{
previous = expression;
continue;
}
Iteration iteration1 = previous.As <Iteration>();
Iteration iteration2 = expression.As <Iteration>();
if (iteration1 != null || iteration2 != null)
{
if (iteration1 != null && iteration2 != null && iteration1.Expression == iteration2.Expression)
{
if (iteration1.IsPositive && iteration2.IsPositive)
{
newList.Add(iteration1.Expression);
}
previous = new Iteration(iteration1.Expression, iteration1.IsPositive || iteration2.IsPositive);
somethingChanged = true;
continue;
}
Iteration iteration;
Expression newExpression;
if (iteration1 != null)
{
iteration = iteration1;
newExpression = expression;
}
else
{
iteration = iteration2;
newExpression = previous;
}
if (iteration.Expression == newExpression && !iteration.IsPositive)
{
previous = new Iteration(newExpression, true);
somethingChanged = true;
continue;
}
}
ConstIteration constIteration1 = previous.As <ConstIteration>();
ConstIteration constIteration2 = expression.As <ConstIteration>();
if (constIteration1 != null || constIteration2 != null)
{
if (constIteration1 != null && constIteration2 != null && constIteration1.Expression == constIteration2.Expression)
{
previous = new ConstIteration(constIteration1.Expression, constIteration1.IterationCount + constIteration2.IterationCount);
somethingChanged = true;
continue;
}
ConstIteration constIteration;
Expression newExpression;
if (constIteration1 != null)
{
constIteration = constIteration1;
newExpression = expression;
}
else
{
constIteration = constIteration2;
newExpression = previous;
}
if (constIteration.Expression == newExpression)
{
previous = new ConstIteration(newExpression, constIteration.IterationCount + 1);
somethingChanged = true;
continue;
}
}
if (constIteration1 != null && iteration2 != null && constIteration1.Expression == iteration2.Expression)
{
if (constIteration1.IterationCount > 2)
{
newList.Add(new ConstIteration(constIteration1.Expression, constIteration1.IterationCount - 1));
}
else
{
newList.Add(constIteration1.Expression);
}
previous = new Iteration(iteration2.Expression, true);
somethingChanged = true;
continue;
}
if (iteration1 != null && constIteration2 != null && iteration1.Expression == constIteration2.Expression)
{
newList.Add(new Iteration(iteration1.Expression, true));
if (constIteration2.IterationCount > 2)
{
previous = new ConstIteration(constIteration2.Expression, constIteration2.IterationCount - 1);
}
else
{
previous = constIteration2.Expression;
}
somethingChanged = true;
continue;
}
newList.Add(previous);
previous = expression;
}
if (previous != null)
{
newList.Add(previous);
}
oldList = newList;
somethingChanged |= TryToCompress(oldList);
} while (somethingChanged);
return(ConcatHelper.MakeExpression(newList));
}
private static bool TryToCompress(IList <Expression> list)
{
bool changed;
bool somethingChanged = false;
do
{
changed = false;
for (int i = 0; i < list.Count; i++)
{
Iteration iteration = list[i].As <Iteration>();
if (iteration == null || iteration.IsPositive)
{
continue;
}
Concat concat = iteration.Expression.As <Concat>();
IList <Expression> list1;
if (concat != null)
{
list1 = concat.Expressions.ToList();
}
else
{
list1 = iteration.Expression.AsSequence().ToList();
}
int j = 0;
IList <Expression> list2 = null;
for (j = 0; j <= list1.Count; j++)
{
if (j > i || list1.Count - j > list.Count - i - 1)
{
continue;
}
list2 = new List <Expression>();
int k;
for (k = 0; k < j; k++)
{
list2.Add(list[i - j + k]);
}
for (k = 0; k < list1.Count - j; k++)
{
list2.Add(list[i + 1 + k]);
}
bool allEquals = true;
for (int l = 0; l < list1.Count; l++)
{
if (list1[l] != list2[(l + j) % list2.Count])
{
allEquals = false;
break;
}
}
if (allEquals)
{
break;
}
}
if (j <= list1.Count)
{
Expression newExpression = new Iteration(ConcatHelper.MakeExpression(list2), true);
for (int l = list1.Count - j; l > 0; l--)
{
list.RemoveAt(i + l);
}
for (int l = 0; l <= j; l++)
{
list.RemoveAt(i - l);
}
i -= j + 1;
list.Insert(i + 1, newExpression);
changed = true;
somethingChanged = true;
}
}
} while (changed);
return(somethingChanged);
}
private static Expression ExtractFromBrackets(Expression expressionA, Expression expressionB)
{
IReadOnlyList <Expression> concatA = expressionA.As <Concat>()?.Expressions;
if (concatA == null)
{
concatA = expressionA.AsSequence().ToList().AsReadOnly();
}
IReadOnlyList <Expression> concatB = expressionB.As <Concat>()?.Expressions;
if (concatB == null)
{
concatB = expressionB.AsSequence().ToList().AsReadOnly();
}
int left = 0;
int right = 0;
int count = Math.Min(concatA.Count, concatB.Count);
while (left < count && concatA[left] == concatB[left])
{
left++;
}
while (right < count - left && concatA[concatA.Count - 1 - right] == concatB[concatB.Count - 1 - right])
{
right++;
}
if (left == 0 && right == 0)
{
return(null);
}
IList <Expression> newConcat = new List <Expression>();
IList <Expression> leftConcat = new List <Expression>();
IList <IList <Expression> > middleUnion = new List <IList <Expression> >();
IList <Expression> rightConcat = new List <Expression>();
for (int i = 0; i < left; i++)
{
leftConcat.Add(concatA[i]);
}
for (int i = 0; i < right; i++)
{
rightConcat.Add(concatB[concatB.Count - 1 - i]);
}
rightConcat = rightConcat.AsReadOnly().FastReverse().ToList();
IList <Expression> middleConcat = new List <Expression>();
for (int i = left; i < concatA.Count - right; i++)
{
middleConcat.Add(concatA[i]);
}
middleUnion.Add(middleConcat);
middleConcat = new List <Expression>();
for (int i = left; i < concatB.Count - right; i++)
{
middleConcat.Add(concatB[i]);
}
middleUnion.Add(middleConcat);
newConcat.AddRange(leftConcat);
newConcat.Add(
UnionHelper.MakeExpression(
middleUnion.Select(
c => ConcatHelper.MakeExpression(c.Where(e => e != Empty.Instance).ToList())
).ToList()
)
);
newConcat.AddRange(rightConcat);
return(ConcatHelper.MakeExpression(newConcat).Optimize());
}